With the advanced transportation of today, there are transportation tools such as bicycles that are compact, lightweight, economical and motorized. Bicycles have not become obsolete, but have undergone continuous improvement through innovative research and development by manufacturers that has enabled them to be effective transportation tools, while also serving as recreation products. Regarding the improvements to various parts of bicycles, the conservation of physical energy when riding has now become among the most important focus of improvement sought by manufacturers and users. How to simply and improve the material structure of the frame, reduce the weight and utilize transmission devices to change front and rear chain sprocket ratios are all ergonomic measures relied upon by manufacturers.
In addition to the aforementioned methods and measures to obtain more effective and safe human interaction when riding, there have been previous attempts to provide devices to ergonomically enhance bicycles. An example is disclosed in U.S. Pat. No. 601,923, showing a device that effectively increases efficiency with an auxiliary crank actively installed onto each pedal crank. The pedals are then installed on the auxiliary cranks such that when the rider places both feet on the pedals, the aforesaid auxiliary cranks follow the bending and lengthening of the legs in a natural manner and at an angle appropriate to provide support. Such thereby enables the actual and effective cancellation of dead angles, dissipating the force exerted by the feet so that the force from the legs is transferred at greater efficiency which effectively succeeds in achieving ergonomic objectives. Therefore, the aforesaid force generated by the motion of the legs and feet are transferred with more fluidity and thereby achieves the objective of compliance with human engineering requirements. The aforesaid Patent was granted because the dead angles encountered by the force of the feet were eliminated and, therefore, genuinely and fully provided effective ergonomic results in actual application (especially the conservation of human energy provided when a bicycle so equipped was ridden uphill). However, the individual registering the aforesaid Patent observed a number of major shortcomings related to the actual installation and utilization that would eventually require improvement. As indicated in U.S. Pat. No. 610,923, the method of installing the aforesaid auxiliary crank onto the pedal crank consists of screwing the extension sleeve onto the threaded adjustment shaft against the anti-friction ball bearings, after which the aforesaid assembly is screwed into the threaded hole of the pedal crank to achieve a mechanical positioning capable of free rotation. However, since the extension sleeve is only assembled to the threaded adjustment shaft via screw-type threads, when the threaded adjustment shaft is screwed to the pedal crank, the extension sleeve is subjected to the mechanical effects of the screwing process and consequently shifts in position. As a result, when the threaded adjustment shaft is tightened, the aforesaid extension sleeve exerts a greater contact force onto the anti-friction ball bearings, which in turn leads to the shortcoming of inhibiting the smooth rotation of the auxiliary crank. In the alternative, if the threaded adjustment shaft is not tightened to a sufficient degree, then the aforesaid shaft is extremely susceptible to loosening, thereby creating a dangerous situation. Therefore, the aforesaid installation requires continuous adjustment and screwing attempts such that in actual operation, the assemblage presents obvious disadvantages of excessive difficulty and inconvenience. Furthermore, since the auxiliary crank is installed onto the pedal crank, after the pedal is installed onto the aforesaid auxiliary crank, the distance between the aforesaid pedal and the ground is reduced and as a direct result, since the ends of the pedal cranks installed on conventional bicycle pedals are close to the ground, the aforesaid auxiliary pedal is only capable of smooth operation when a bicycle so equipped is ridden in a straight line. However, when the aforesaid bicycle is leaned over during the execution of a turn, the end of the aforesaid pedal poses the dangerous situation of easily making contact with the ground. Therefore, as disclosed in the foregoing elaboration, the auxiliary crank component of the aforesaid U.S. Pat. No. 610,923 is not only characterized by the shortcoming of difficult and inconvenient installation, but also has the disadvantage of being dangerous in actual utilization. Meanwhile, a certain manufacturer once introduced a device similar in nature to that of U.S. Pat. No. 610,923. In U.S. Pat. No. 558,463, the pedal is indirectly installed to the pedal crank. However, the invention of the aforesaid Patent only consisted of installing a yoke to modify the length of the pedal crank. However, since the aforesaid yoke was mounted in an immovable configuration and, therefore, was incapable of free rotation, the aforesaid yoke was essentially precluded from eliminating the dead angles to the force exerted by the feet, and thereby offered no ergonomic advantage in bicycle riding.